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Property guide · Westminster

1930s semi-detached extensions in Westminster

Bay-fronted suburban semis with hipped roofs and side passages. Dominant outer-London stock.

Quick facts

Property type
1930s semi-detached
Borough
Westminster
Planning authority
Westminster City Council
Article 4 in force
Yes
Conservation areas
56
Drawings from
£840

1930s semi-detached stock in Westminster responds best to extensions that respect the existing rhythm. For Victorian and Edwardian period property, side returns and rear infill are routine. For 1930s suburban, single-storey rear and loft conversions dominate. We design to the block, not the brochure.

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Which postcode districts around Westminster do we cover for 1930s semi project work?

Every Westminster postcode district we draw in, the stock that dominates it and the authority that validates a 1930s semi project there. Westminster fees below are the statutory England rates for 2026, not 1930s semi project estimates.

PostcodeAreaDominant stockWhat it means for a 1930s semi project
SW1HSt James's ParkGrand Georgian and Regency terraces in Belgravia and Pimlico; Victorian and Edwardian mansion blocks; heritage-rich townhouses throughout; very high listed building densitySW1H covers St James's Park only; Westminster City Council handles the 1930s semi project, and St James's Park case officers apply the SW1H conservation-area map.
SW1PWestminster / Vincent SquareGrand Georgian and Regency terraces in Belgravia and Pimlico; Victorian and Edwardian mansion blocks; heritage-rich townhouses throughout; very high listed building densityWestminster / Vincent Square sits wholly inside SW1P, so Westminster City Council validates every 1930s semi project submitted from an SW1P address.
SW1VPimlicoRegency terraces, post-war estatesA 1930s semi project at an SW1V address in Pimlico is determined by Westminster City Council under its own Local Plan policies for Pimlico.
SW1WBelgravia / VictoriaRegency stucco terraces, listed buildingsSW1W covers Belgravia / Victoria only; Westminster City Council handles the 1930s semi project, and Belgravia / Victoria case officers apply the SW1W conservation-area map.
SW1XKnightsbridge / BelgraviaRegency stucco terraces, listed buildingsKnightsbridge / Belgravia is split at SW1X. Either Westminster City Council or RBKC Planning can determine a 1930s semi project here, so the SW1X address is checked against both policies maps first.
SW1YSt James'sGrand Georgian and Regency terraces in Belgravia and Pimlico; Victorian and Edwardian mansion blocks; heritage-rich townhouses throughout; very high listed building densitySt James's sits wholly inside SW1Y, so Westminster City Council validates every 1930s semi project submitted from an SW1Y address.
W1BRegent StreetGrand Georgian and Regency terraces in Belgravia and Pimlico; Victorian and Edwardian mansion blocks; heritage-rich townhouses throughout; very high listed building densityW1B covers Regent Street only; Westminster City Council handles the 1930s semi project, and Regent Street case officers apply the W1B conservation-area map.
W1DSohoGeorgian terraces, mixed-useSoho sits wholly inside W1D, so Westminster City Council validates every 1930s semi project submitted from an W1D address.

What changes about a 1930s semi project in each part of Westminster?

Roof pitch, wall build-up and plot depth change every few Westminster streets, and each one changes what a 1930s semi project can achieve at that address.

How do conservation areas and Article 4 affect a 1930s semi project in Westminster?

Westminster conservation designations: there are 56 across Westminster City Council, Pimlico, Soho, Covent Garden among them. Designation costs a Westminster owner the permitted-development route: a 1930s semi project then needs a £258 householder application over 8 weeks, in place of the £120 prior approval route that takes 6 weeks. Covent Garden is the Westminster designation that most often changes a 1930s semi project design.

Westminster and Article 4: Multiple Article 4 Directions — office-to-residential restrictions, HMO conversions, retail to residential in shopping zones. A 1930s semi project planned at a NW8 address is checked against that direction first; Westminster City Council publishes the Westminster extent, and the NW8 line rarely follows the Westminster boundary you would expect.

Digging below a Westminster property: Westminster basement policy restricts to single-storey, typically under 50% of rear garden footprint; lightwells and rooflights strictly controlled in conservation areas. Where a 1930s semi project in Westminster involves excavation that is read beside the Party Wall etc. Act 1996, which needs two months notice for a Westminster dig within 3 m of a neighbour, and Westminster City Council expects the NW8 ground conditions addressed in the application.

Westminster housing stock: Grand Georgian and Regency terraces in Belgravia and Pimlico; Victorian and Edwardian mansion blocks; heritage-rich townhouses throughout; very high listed building density. Heritage-first planning approach; listed buildings on almost every street; basement and rear extension policies particularly strict. Read that before choosing a 1930s semi project route in Westminster — construction, not postcode, sets what is achievable. 1930s semi projects in Westminster start at £840 on a fixed fee, or £1,750 for the Complete package covering both Westminster City Council submissions.

What happens if a Westminster property sits on a boundary?

Sources for this Westminster 1930s semi project page: borough policies maps and conservation-area registers (2025–26), Royal Mail postcode district boundaries, the Town and Country Planning (Fees for Applications) (England) Regulations, the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended, and the Party Wall etc. Act 1996.

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